Dr. Dorothy J. T. TermanAlbuquerque, NMEllen GraceScience Curriculum Development ConsultantFormer K–12 Science and Mathematics CoordinatorIrvine Unified School District, CAThe American Museum of Natural History in New
York City is one of the world’s preeminentscientific, educational, and cultural institutions, with a global mission to explore and interprethuman cultures and the natural world through scientific research, education, and exhibitions. Each year theMuseum welcomes around four million visitors, including 500,000 schoolchildren in organized field trips. Itprovides professional development activities for thousands of teachers; hundreds of public programs thatserve audiences ranging from preschoolers to seniors; and an array of learning and teaching resources foruse in homes, schools, and community-based settings. Visit www.amnh.org for online resources.Students with print disabilities may be eligible to obtain an accessible, audio version of the pupil editionof this textbook. Please call Recording for the Blind & Dyslexic at 1-800-221-4792 for complete information.BPublished by Macmillan/McGraw-Hill, of McGraw-Hill Education, a division of The McGraw-Hill Companies, Inc.,Two Penn Plaza, New
York 10121.Copyright © 2008 by Macmillan/McGraw-Hill. All rights reserved. No part of this publication may bereproduced or distributed in any form or by any means, or stored in a database or retrieval system,without the prior written consent of The McGraw-Hill Companies, Inc., including, but not limited to,network storage or transmission, or broadcast for distance learning.Science Content Standards for California Public Schools reproduced by permission, California Departmentof Education, CDE Press, 1430 N Street, Suite 3207, Sacramento, CA 95814.